Write once, read many (WORM) storage is a data storage technology that allows data to be written to storage media a single time and not rewritten thereafter to prevent tampering of the stored data. WORM storage traditionally used optical media, but recent innovations have applied WORM storage to other storage technologies, such as tape storage and hard disk drives. WORM storage has been used for archiving data that requires a long retention period (e.g., medical information), but driven by the recent growth of legislation in many countries, WORM storage is now increasingly being used to archive corporate data, such as financial documents and emails.
It should be appreciated there are a variety of different implementations of WORM storage, and many WORM storages require the creation of separate aggregates of storage devices for all the different implementations. For example, if three different types of WORM storage implementations are needed, then three different aggregates need to be created. The requirement of separate aggregates for each different type of implementation may result in the inefficient utilization of storage devices. For example, the creation of each aggregate creates a certain Redundant Arrays of Independent Disks (RAID) overhead. Additionally, a minimum of three storage devices are required to create an aggregate in some RAID implementations, such as Double Parity RAID 6, and a typical storage system may not have this number of free storage devices available. Furthermore, a large number of aggregates may not have adequate capacity utilization.